DESC:FORM 2
THE PATENT ACT 1970
(39 of 1970)
&
THE PATENT RULES, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)

“PROCESS FOR PREPARATION OF HYDROFLUOROOLEFINS”

SRF LIMITED, AN INDIAN COMPANY,
SECTOR 45, BLOCK-C, UNICREST BUILDING,
GURGAON – 122003,
HARYANA (INDIA)

The following specification particular describe the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION
The present invention relates to a process for preparation of hydrofluoroolefins.

BACKGROUND OF THE INVENTION
Hydrofluorocarbon, widely used as refrigerants, heat transfer fluids, foam blowing agents, solvents, and aerosols, are being phased out and replaced by hydrofluoroolefins (HFO) due to their high global warming potential.
European Patent No. 3176147 provides a method for preparing trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E) by de-hydrofluorinating 1,1,1,3,3-pentafluoropropane (245fa) to produce a mixture of cis-1,3,3,3-tetrafluoropropene, trans-1,3,3,3-tetrafluoropropene and hydrogen fluoride, followed by distillation to recover trans-1,3,3,3-tetrafluoropropene.
US Patent No. RE48889 provides a method for preparing HFO-1234ze(E), comprising a step of contacting a mixture of 1,1,1,3,3-pentafluoropropane and Z-1,3,3,3-tetrafluoropropene in a gas phase with a fluorinated chromia or alumina in presence of an oxygen containing gas, to supress HFO-1234ze(Z) and maximise the recovery of HFO-1234ze(E).
European Patent No. 2247560 provides a method for preparing 1,3,3,3-tetrafluoropropene comprising a step of separating hydrogen fluoride from a mixture of 1,3,3,3-tetrafluoropropene and hydrogen fluoride by azeotropic distillation of a composition comprising 1,3,3,3-tetrafluoropropene and hydrogen fluoride followed by condensation of the distillate to separate two liquid phases.
Japanese Patent No. 5136111 provides a method for preparing 1,3,3,3-tetrafluoropropene comprising a step of separating hydrogen fluoride from a mixture of 1,3,3,3-tetrafluoropropene and hydrogen fluoride by contacting the mixture with sulfuric acid.
However, there remains a need to develop an efficient process for preparation of 1,3,3,3-tetrafluoropropene. The present invention provides a simple process for preparation and isolation of 1,3,3,3-tetrafluoropropene.

OBJECT OF THE INVENTION
The present invention provides an efficient process for preparation and isolation of 1,3,3,3-tetrafluoropropene.

SUMMARY OF THE INVENTION
In an aspect, the present invention provides a process for preparation of 1,3,3,3-tetrafluoropropene (1234ze), comprising the steps of:
a) fluorinating a mixture comprising 1,1,1,3,3-pentachloropropane with hydrogen fluoride to obtain a mixture comprising 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd);
b) reacting the mixture comprising HCFO-1233zd with a fluorinating agent in presence of a catalyst in liquid phase to obtain a composition comprising 1,1,1,3,3-pentafluoropropane (245fa);
c) de-hydrofluorinating a composition comprising 245fa in presence of a catalyst to obtain 1234ze;
d) treating 1234ze with a solution of alkali and a drying agent selected from a group consisting of ethylene glycol, propylene glycol, isopropylene glycol, glycerol, diethylglycol, or triethylglycol; and
e) isolating 1234ze.

DETAILS DECRIPTION OF THE INVENTION
In an embodiment of the present invention, the step of de-hydrofluorination is performed at a temperature in the range of 300-400 ?.
In another embodiment of the present invention, the step of de-hydrofluorination is carried out in presence of a catalyst selected from a group consisting of fluorinated chromia, fluorinated chromia-alumina, fluorinated alumina, activated carbon or the like.
In another embodiment of the present invention, 1234ze obtained through distillation is treated with a solution of alkali.
As used herein, a solution of alkali refers to sodium hydroxide and potassium hydroxide. Preferably 5% NaOH or 5% KOH solution.
In another embodiment of the present invention, 1234ze obtained through distillation is treated with a polyhydric alcohol selected from a group consisting of ethylene glycol, propylene glycol, isopropylene glycol, glycerol, diethylglycol, triethylglycol or the like to obtain 1234ze having moisture content of 0 to 0.0010%.
In another embodiment of the present invention, excess of anhydrous hydrogen fluoride which is recycled back to the reactor.
In another embodiment of the present invention, 1,1,1,3,3-pentachloropropane (240fa) is obtained by a process, comprising the steps of:
a) heating 1,2-dichloroethane at a temperature of 200-600? to obtain a mixture comprising vinyl chloride;
b) reacting the mixture containing vinyl chloride with carbon tetrachloride in presence of a catalyst to obtain a mixture comprising 1,1,1,3,3-pentachloropropane;
In another embodiment of the present invention, the step of fluorinating 1,1,1,3,3-pentachloropropane with hydrogen fluoride is carried out in presence of oxygen or air.
In another embodiment of the present invention, the step of fluorinating 1,1,1,3,3-pentachloropropane with hydrogen fluoride is carried out in presence of 0.01 to 0.1% of oxygen.
In another embodiment of the present invention, the mixture comprising 1233zd is reacted with hydrogen fluoride in presence of a Lewis acid catalyst selected from a group consisting of antimony halides, tin halides and antimony mixed halides selected from a group consisting of tin tetrachloride, antimony trichloride, antimony pentachloride, antimony fluorochlorides or the like.
In another embodiment, the step of reacting vinyl chloride with carbon tetrachloride is carried out in presence of ferric chloride/tributylphosphate/iron powder as catalyst complex to obtain a mixture comprising 1,1,1,3,3-pentachloropropane.
In another embodiment, a feed comprising 240fa is reacted with a fluorinating agent in presence of catalyst in vapour phase to obtain a reaction mixture comprising 1-chloro-3,3,3-trifluoropropene.
The fluorination is carried out at a temperature of 200-300? and a pressure of 10 Kg/cm2 to 20Kg/cm2. The step of fluorination is carried out using an anhydrous hydrogen fluoride as fluorinating agent in a vapour phase.
In another embodiment, the fluorination of 240fa using anhydrous hydrogen fluoride is carried out in tubular reactor having material of construction selected from Hastelloy, Inconel or like, that are resistant to corrosion.
The step of isolation involves a procedure selected from a group consisting of washing, layer separation, treatment with alkali, distillation, or a combination of these.
In another embodiment of the present invention, the step of isolation involves contacting the reaction mixture with a compound selected from a group consisting of 1,1,1,3,3-pentachloropropane; 1,1,1,3,3-pentafluoropropane; 1,2-dichloroethane; carbon tetrachloride, to separate hydrogen fluoride layer and an organic layer.
In another embodiment of the present invention, the step of isolation involves distillation carried out atmospheric pressure to 10 bar g pressure to obtain a composition of more than 99.5 % R-1234ze
Unless stated to the contrary, any of the words “comprising”, “comprises” mean
“including without limitation” and shall not be construed to limit any general statement that it follows to the specific or similar items or matters immediately following it.
Embodiments of the invention are not mutually exclusive but may be implemented in various combinations. The described embodiments of the invention and the disclosed examples are given for the purpose of illustration rather than limitation of the invention as set forth in the appended claims.
The completion of the reaction can be monitored by any one of chromatographic techniques such as thin layer chromatography (TLC), high pressure liquid chromatography (HPLC), ultra-pressure 5 liquid chromatography (UPLC), Gas chromatography (GC) and alike.
The following examples are given by way of illustration and therefore should not be construed to limit the scope of the present invention.

EXAMPLE
Example 1: Preparation of vinyl chloride.
1,2-Dichloroethane was thermally cracked in a tubular reactor at 400-500? to obtain vinyl chloride. The product was isolated from tubular reactor.
Example 2: Preparation of 1,1,1,3,3-pentachloropropane (240fa)
An autoclave reactor was charged with ferric chloride/tributylphosphate/iron powder as catalyst complex and some amount of carbon tetrachloride. Carbon tetrachloride and vinyl chloride were simultaneously added into the reactor and heated at 90-100? at a pressure of 3-4Kg/cm2 to obtain crude product. The crude product was distilled to obtain 1,1,1,3,3-pentachloropropane. Conversion: >96.5%; Selectivity: >92.8%
Example 3: Preparation of trans-1-chloro-3,3,3-trifluoropropene (trans-1234ze)
1,1,1,3,3-pentachloropropane (240fa) and anhydrous hydrogen fluoride were preheated at a temperature of 110-150?, mixed and reacted in a tubular reactor at 200-300? at a pressure of 10Kg/cm2 in vapour phase in the presence of fluorinated chromia catalyst. The reactor outlet was connected to a distillation column from where, a top stream comprising hydrogen chloride was removed by simple distillation as mentioned in GB2313118A and subsequent mixture was fluorinated by continuously adding hydrogen fluoride and in another reactor in liquid phase using fluorinated antimony pentachloride, as catalyst, to obtain 1,1,1,3,3-pentafluoropropane (245fa) at 70-100? at a pressure at 2-5 kg/cm2. The crude 245fa was dehydrofluorinated to form 1234ze using fluorinated chromia in vapour phase at 350 to 400? at a pressure of 0-1 kg/cm2. The dehydrofluorinated product was washed with water followed by caustic solution. The product mixture was then passed through diethyl glycol and sent to a distillation column to isolate R-1234ze (Trans) as top stream and 245fa along with intermediate remain in the distillation bottom which is recycled back into the reactor. Analysis: Trans-1234ze (GC Purity): 99.5%
Example 4: Preparation of trans-1,3,3,3-tetrafluoropropene (trans-1234ze)
1233zd (obtained commercially; or prepared following an example of GB2313118A) and hydrogen fluoride were continuously added to a reactor maintained at a temperature of 70-100? and pressure of 2-5 kg/cm2 in presence of a fluorinated antimony pentachloride, as catalyst, to obtain 1,1,1,3,3-pentafluoropropane (245fa). The crude 245fa was dehydrofluorinated to form 1234ze using fluorinated chromia vapour at 350 to 400? and at a pressure of 0-1kg/cm2. The dehydrofluorinated product was washed with water followed by caustic solution and then passed through diethyl glycol and sent to a distillation column to isolate R-1234ze (Trans) as top stream and 245fa along with intermediate remain in the distillation bottom which is recycled back into the reactor. Analysis:
Conversion : >40 % and R-1234ze Selectivity : >99 %.
Example 5: Preparation of trans-1,3,3,3-tetrafluoropropene (trans-1234ze)
245fa (obtained commercially; or prepared following an example of GB2313118A) was dehydrofluorinated to form 1234ze using fluorinated chromia vapour at 350 to 400? and at a pressure of 0-1kg/cm2. The dehydrofluorinated crude product was washed with water followed by caustic solution and then passed through diethyl glycol and sent to a distillation column to isolate R-1234ze (Trans) as top stream and 245fa along with intermediate remain in the distillation bottom which is recycled back into the reactor. Analysis: Trans-1234ze (GC Purity): 99.1%
Example 6: Preparation of trans-1,3,3,3-tetrafluoropropene (trans-1234ze)
The example disclosed in examples 1-2 of JP3886229B2 were followed to prepare the 1,3,3,3-tetrafluoropropene to obtain a mixture of trans and cis forms, the cis form has a boiling point close to that of the starting 1,1,1,3,3-pentafluoropropane and is not easily separable because it behaves like an azeotrope. Therefore, a mixture (product) consisting of a trans-isomer of a 1,3,3,3-tetrafluoropropene, a cis-isomer and a 1,1,1,3,3-pentafluoropropane was distilled to recover only a trans-isomer, which was washed with water followed by caustic solution, then passed through diethyl glycol and sent to a distillation column to isolate R-1234ze.
The remaining cis-isomer and the 1,1,1,3,3-pentafluoropropane can be subjected to the reaction of the present invention again without separating the residual cis-isomer.

,CLAIMS:WE CLAIM:
1. A process for preparation of 1,3,3,3-tetrafluoropropene (1234ze), comprising the steps of:
a) fluorinating a mixture comprising 1,1,1,3,3-pentachloropropane (240fa) with hydrogen fluoride to obtain a mixture comprising 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd);
b) reacting the mixture comprising HCFO-1233zd with a fluorinating agent in presence of a catalyst in liquid phase to obtain a composition comprising 1,1,1,3,3-pentafluoropropane (245fa);
c) de-hydrofluorinating a composition comprising 245fa in presence of a catalyst to obtain 1234ze;
d) treating 1234ze with a solution of alkali and a drying agent selected from a group consisting of ethylene glycol, propylene glycol, isopropylene glycol, glycerol, diethylglycol, or triethylglycol; and
e) isolating 1234ze.
2. The process as claimed in claim 1, wherein the step of de-hydrofluorination is performed at a temperature in the range of 300-400?.
3. The process as claimed in claim 1, wherein the step of de-hydrofluorination is carried out in presence of a catalyst selected from a group consisting of fluorinated chromia, fluorinated chromia-alumina, fluorinated alumina and activated carbon.
4. The process as claimed in claim 1, wherein the 1234ze obtained through distillation is treated with a polyhydric alcohol selected from a group consisting of ethylene glycol, propylene glycol, isopropylene glycol, glycerol, diethylglycol and triethylglycol to obtain 1234ze having moisture content of 0 to 0.0010%.
5. The process as claimed in claim 1, wherein the excess of anhydrous hydrogen fluoride is recycled back to the reactor.
6. The process as claimed in claim 1, wherein the step of fluorinating 1,1,1,3,3-pentachloropropane with hydrogen fluoride is carried out in presence of 0.01 to 0.1% of oxygen or air.
7. The process as claimed in claim 1, wherein the mixture comprising 1233zd is reacted with hydrogen fluoride in presence of a Lewis acid catalyst selected from a group consisting of antimony halides, tin halides and antimony mixed halides selected from a group consisting of tin tetrachloride, antimony trichloride, antimony pentachloride and antimony fluorochlorides.
8. The process as claimed in claim 1, wherein the step of isolation involves contacting the reaction mixture with a compound selected from a group consisting of 1,1,1,3,3-pentachloropropane; 1,1,1,3,3-pentafluoropropane; 1,2-dichloroethane; carbon tetrachloride, to separate hydrogen fluoride layer and an organic layer.
9. The process as claimed in claim 1, wherein the step of isolation involves distillation carried out at atmospheric pressure to 10 bar g pressure to obtain a composition of more than 99.5 % R-1234ze.

Dated this 26th day of September 2022.